Space-Based Surveillance and Tracking System (SSTS)
The SDI's layered defense against ballistic missiles would require a space-based sensor system to find nuclear warheads in the post-boost and midcourse phases. The proposed Space Surveillance and Tracking System [SSTS] would acquire and track post-boost vehicles and nuclear warheads and discriminate warheads from a significantly larger quantity of decoys and debris. SSTS has four major functions during the post-boost and midcourse phases: to (1) acquire and track threat objects, (2) discriminate warheads from decoys and debris, (3) provide target location information to other systems, and (4) assist in damage assessment of targets. The SSTS would also serve a surveillance role for the U.S. "space defense" mission. Under this mission, the SSTS would provide surveillance support to U.S. antisatellite weapons, warn of attacks on U.S. satellites, and monitor and catalog all objects in orbit around the earth.
Several dozen spacecraft would supply adequate coverage around the world for submarine-launched missiles. Redundancy would be necessary for survivability and for stereo viewing of the targets. These SSTS satellites might be essential for much of the mid-course battle, so some SSTSS must survive at most locations.
The SSTS satellites would carry one or more long-wave infrared (LWIR) sensors for tracking the somewhat warm PBVs and cold RVs. These LWIR sensors could not detect RVs by looking straight down against the relatively warm earth background. Rather, they would look only above the horizon, in a conical or "coolie hat" pattern which would afford the necessary cold space background for the IR detectors. Thus each SSTS would monitor targets that were far from the satellite. Those targets closest to each SSTS would pass below its sensors, undetected; they would have to be observed by more distant SSTS satellites. This problem could be alleviated if sensing at other wavelengths, e.g., in the visible range, were to be feasible.
For some missions, such as cueing DEW sensors, the SSTS might include short-wave infrared (SWIR) and medium-wave infrared (MWIR) sensors to track booster exhaust plumes. This would duplicate to some extent the BSTS function, but with much better resolution. These sensors might have limited fields of view, so that each SSTS platform would require several IR sensors to cover all the threats. These SWIR/MWIR sensors could look down against the Earth background, since they would be monitoring the hot plumes. Several architects recommended placing laser systems (and some suggested microwave radars) on the SSTS. Lasers might be needed to designate or illuminate targets for homing space-based interceptors (SBIs). Laser radar (Ladar) systems might be required for all of the interactive discrimination systems, just to determine the target's position with sufficient accuracy. This would be particularly true for tracking cold RVs, which could be passively detected mainly by LWIR sensors with inherently poor resolution, or for discriminating and designating an RV in the presence of closely spaced objects (that often are decoys). In any case, a laser radar could supply the range to the target, which is necessary to generate three dimensional track files from a single platform.
To assess the feasibility of achieving this space-based surveillance capability, SDIO budgeted $102.4 million for fiscal years 1985 through 1987 for the SSTS program, which was managed by the Air Force's Space Division. The requested budget for fiscal year 1988 is $170.8 million and for fiscal year 1989, $210.8 million. SSTS's success also depends on several technology base programs that are separately funded and support several other sensor programs in addition to the SSTS. The fiscal years 1988 and 1989 budget requests for these technology programs are $295.5 miilion and $326.8 million, respectively.
In July 1987, the SSTS program concluded its initial phase of determining requirements and investigating preliminary system concepts. Changing development approaches, or plans, extended this initial phase. The midcourse sensor study occurred from September through December 1987. This study was to support a January 1988 SDIO d ecision on what mix of sensors was appropriate to cover the midcourse in an initial SD1 deployment. The study is also to define a technology development path to a more capable future system and to identify experiments that will demonstrate the feasibility of midcourse surveillance and tracking.
The program had three different development plans in 3 years and cost over $100 million by the end of fiscal year 1987. The SDIO originally awarded g-month contracts to three companies, totalling $12 million, to define requirements and preliminary concepts. These contracts were extended to nearly 3 years at a cost of $65 million. Other program support costs consumed the remainder of the $102.4 million.
The first development plan was designed to satisfy a space defense surveillance role and a limited initial ballistic missile defense (BMD) surveillance role. The second development plan called for increasing the BMD capability of the initial system. This plan was ultimately judged too costly and complex. The third and current plan, effective in February 1987, was again for a limited, initial BMD capability. Under this plan, contracts for the definition of preliminary concepts and mission requirements were completed in July 1987.
Two contractors were awarded follow-on contracts in July 1987 to develop the system concept and continue analyses of SSTS requirements as threat, technology, and architecture evolve. Subsequent contract options are to cover the more costly later stages of design and demonstration of an ssw and a prototype space experiment. Development cost estimates total $966 million for fiscal years 1988 through 1990. A contract for subsequent fabrication, testing, and flight of the space experiment would be awarded to a single contractor. An estimated cost of about $681 million is being used until more reliable estimates for the experiment can be made.
The switch to Brilliant Pebbles in 1990 resulted in a net decrease of $8.1 billion in the estimated cost of four other Phase I Strategic Defense System cost elements: the Space-Based Surveillance and Tracking System decreased $4.2 billion. The estimated cost of the Space Surveillance and Tracking System (SSTS) decreased 46 percent, from $9.2 billion to $5 billion. The decrease is attributed to changes in the function SSTS is expected to perform in the Phase I Strategic Defense System. According to SDIO, the role of SSTS changed considerably with the substitution of Brilliant Pebbles for the Space-Based Interceptor.
In the October 1988 Space-Based Interceptor architecture, SSTS's role was to provide information to the Space-Based Interceptor. Its primary mission was to track targets and support weapon engagement. The SSTS satellites were to provide weapon target assignment, fire control, and in-flight updates for the Space-Based Interceptor and Ground-Based Interceptor systems during the post-boost and early midcourse phases. The SSTS track data would also be used to cue Ground-Based Surveillance and Tracking System and the Ground-Based Radar. In the October 1989 Brilliant Pebbles architecture, SSTS's mission was redefined. It will now be used for surveillance and data collection. The number of SSTS satellites to be launched decreased. This reduced the launch coats by 57 percent, from $1.4 billion to $0.6 billion.
The Strategic Defense Initiative Organization planned to conduct Demonstration/Validation tests of the Space Surveillance and Tracking System [SSTS] technology. These tests were to demonstrate the ability of the technology to perform required tasks, and would validate a future decision on whether to proceed with Full-Scale Development. Demonstration/Validation tests were to be conducted at the Arnold Engineering Development Center, Nevada Test Site, Vandenberg Air Force Base/Western Test Range, Cape Canaveral Air Force Station/Eastern Test Range, Kennedy Space Center, National Test Facility, and at contractor facilities. Tests would include analyses, simulations, component/assembly tests, and flight tests.
The Space Surveillance and Tracking System (SSTS) development program provided an excellent example of how early participation by T&E experts contributed to the early identification of critical system and test facility components. The early involvement of all participating organizations in the Test and Evaluation (T&E) process is important to the success of the weapon system development program. The identification of critical technological and test needs, particularly with respect to space systems, of both the weapon system and the ground test facility require early organizational participation. The guidance provided by the Department of Defense and the Air Force is clear and comprehensive. Test and Evaluation Master Plans and Test Planning Working Groups must be continually emphasized and utilized. With respect to test facilities, requirements must be identified early.
The Space Surveillance and Tracking System (SSTS) remained an SDI program, but it went through several restructurings and changes in concept. The program's flight experiments were canceled, and its planned constellation of satellites became smaller and cheaper. In July 1990, the SDIO renamed the program Brilliant Eyes, and Brilliant Eyes became a far simpler system as interest shifted from protection against Soviet strategic missiles toward protection against shorter range, third-world missiles. In FY 1995, funding for Brilliant Eyes was reduced, and the program's development efforts were cut back.
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